Wash the fennel and cut it in the middle. Then cut into thin slices and roughly chop the cabbage. Cut the onion into very fine cubes. Cook the lentils according to the instructions and pour them over the mixture while still warm. Dice the cucumber and add to it. Add the mustard, vinegar and oil and season with salt, pepper and herbs. Mix everything well.
Wash the lamb`s lettuce and distribute it on plates. Pour the lentil and fennel mixture over it.
Tip:
You can, for example, sprinkle sprouts or seedlings over it.